Cardiac surgeons first began to attempt operative correction of valvular lesions of the heart in the late 1940's. At that time adequate results could not be achieved by the then-available repair or reconstructive procedures, and it became evident that a replacement for the diseased natural valve was required. Work in the early 1950's focused on the descending aorta ball valve and the first successful placement of a prosthetic cardiac valve in a normal anatomical position occurred in March of 1960. Since that time, many investigators have grappled with the design and evaluation problems associated with prosthetic heart valves. A myriad of designs have come and gone but relatively few such designs enjoy clinical popularity at this time. Significant postoperative problems accompany even the best valves now available and the search for a prosthetic valve with better function and decreased incidence of complications continues.
Currently available valve prostheses are of two types; trileaflet valves fabricated from biological tissues or man-made mechanical valves. The biological valves have a tendency for failure due to stiffening and calcification of the leaflets while the mechanical valves have a tendency to cause dangerous clot formation at hinge points. Moreover, many of these mechanical valves have an unacceptably high opening pressure gradient. The present invention features the low opening pressure gradient and freedom from clot formation of the biological trileaflet valves combined with the durability of a mechanical valve.
The following U.S. Patents disclose various forms of construction of trileaflet type prosthetic heart valves:
______________________________________ Inventor Pat. No. ______________________________________ Geeraert 2,822,819 High et al 3,320,972 Schulte 3,445,916 Parsonnet 3,744,062 Hancock 3,755,823 Boretos et al 4,222,126 ______________________________________
Many manifestations of valvular disease of the heart are presently amenable to correction by the use of a prosthetic device to simulate the hemodynamic functioning of a natural valve. However, presently available valvular prostheses do not simulate the anatomic functioning of the natural valve and indeed, flow characteristics are generally far from that seen in the natural valve. As a consequence of the departure from the natural state, postoperative complications appear. These complications can be classified into five major areas: thromboembolic; functional; technical; anatomical; and hemolysis.